The present invention relates to a denture base provided with a lining layer having rubber-like resilience and a process for producing the same.
It has hitherto been known that a lining layer having rubber-like resilience or flexibility is formed on the inner surface of a denture base body in order to make the support of the dental prosthesis to patient's alveolus ridge stable and strong and in order to prevent a shake, an undesirable pain and falling off at time of chewing. The materials used for the lining layer are, for instance, a mixed material of vulcanized rubber and plastic material (U.S. Pat No. 3,083,459 or U.S. Pat. No. 3,886,659), silicone rubber (U.S. Pat. No. 3,251,910 or U.S. Pat. No. 3,667,123), hydrogel (U.S. Pat No. 3,628,988 or U.S. Pat. No. 3,930,076), EVA (U.S. Pat. No. 3,727,309), a mixture of MMA polymer, MMA monomer and butyl phthalyl butylglycolate (U.S. Pat. No. 3,969,303), polyurethane (U.S. Pat. No. 4,024,636), fluorine elastomer (U.S. Pat. No. 4,251,215 or U.S. Pat. No. 4,484,894), and the like. Further, a material comprising MMA is disclosed in U.S. Pat. No. 2,457,114.
However, when the above-mentioned materials are used for a lining layer, there are some disadvantages as follows:
1. In case that a soft resin is used for a lining layer, it is unsuitable to support the attachment, since the rubber-like resilient is restricted. Further, when a pressure face is locally applied onto the lining layer and the lining layer is deformed, the lining layer cannot restore to an original form like a rubber.
2. In case that a lining layer which is a thin sheet is attached and pressed onto the inner surface of a denture base, it is difficult to fill the undercut portion which is inclined toward the alveolus ridges of a natural tooth with the lining layer and the lining layer is not sufficiently supported by natural teeth.
3. Since rubbers such as silicone rubbers are valcanized, it is difficult to process these rubbers after the formation of a lining layer.
The present invention is directed to eliminate the above-mentioned disadvantages. That is to say, a main object of the present invention is to provide a denture base having a lining layer which can be easily formed and processed by conducting a novel thermoplastic elastomer as a material used for the lining layer without any special apparatus.